Field of the Invention
The invention relates to an induction cable containing a plurality of cable cores which each have a conductor strand which is surrounded by insulation. The conductor strand contains a plurality of conductor sections which are spaced apart by respectively insulating intermediate regions with at least one insulating intermediate piece at resonance separation points in a cable longitudinal direction. The invention further relates to a coupling device for an induction cable of this kind, and also to a method for producing an induction cable of this kind.
An induction cable of this kind, also called an inductor, serves to form one or more so-called induction fields. In this case, the induction cable is provided, in particular, for inductively heating oil sand and/or ultra-heavy oil deposits. An application of this kind for an induction cable of this kind can be found, for example, in European patent EP 2 250 858 B1, corresponding to U.S. Pat. No. 8,766,146. The technical boundary conditions resulting from this application are met by the induction cable.
In order to build up the induction fields and implement inductive heating, it is necessary for the individual cable cores of the cable to be separated at defined separation points into contact spacing with a defined length of, for example, several tens of meters. In the process, each of the cable cores is subdivided by the separation points into a number of core sections.
Within the cable, a plurality of cable cores is preferably combined to form core groups, wherein the separation points or interruptions of the cores of a respective core group are situated substantially at the same longitudinal position. There are typically two core groups, the separation points of the core groups being shifted by half the contact spacing relative to one another. In other words: the separation points of a first core group are arranged at half the distance between two separation points of a second core group in the longitudinal direction. As a result, the core sections of different groups overlap, this serving, in particular, to form an induction cable.
A cable of this kind is described, for example, in international patent disclosure WO 2013 079 201 A1, corresponding to U.S. patent publication No. 2014/0263289. This document discloses a cable core for a cable, in particular for an induction cable, containing a plurality of cable cores of this kind which each have a conductor which is surrounded by insulation. Furthermore, the respective cable core, that is to say a conductor which is surrounded by an insulation sheath, is interrupted at prespecified longitudinal positions at separation points in the cable longitudinal direction so as to form two core ends. In order to connect the core ends, a connector containing an insulating intermediate piece is provided and the core ends are fastened to the connector on both sides of the intermediate piece. In order to connect the core ends, the connector is of sleeve-like design at its opposite end sides, so that a respective core end, that is to say also a portion of the insulation sheath in particular, is surrounded.
Induction cables of this kind are usually drawn into the induction field in prepared pipes. The length of a respective induction cable is from several hundred meters to kilometers in this case.
In this case, an induction cable of this kind is typically made up of a plurality of core bundles which are, in particular, braided together. In this case, the overall braided composite typically has a diameter in the range of several centimeters, for example in the range of from 5 to 20 cm.
Providing and laying an encompassing induction cable of this kind is technically complicated.